Name: laser-assisted lentiviral gene delivery to mouse fertilized eggs
Uploaded: 2018-11-01T14:30:00
Description: Watch this Scientific Journal Video about Laser-assisted Lentiviral Gene Delivery to Mouse Fertilized Eggs at JoVE.com

This research was supported by the Intramural Research Program of the National Institute of Health (NIH), National Institute of Environmental Health Sciences (NIEHS). We are grateful to Dr. Robert Petrovich and Dr. Jason Williams for critical reading of the manuscript and helpful advice. We would also like to acknowledge and thank Dr. Bernd Gloss, the Knockout core, the Flow Cytometry Facility, the Fluorescence Microscopy and Imaging Center, and the Comparative Medicine Branch facilities of the NIEHS for their technical contributions. We would like to thank Mr. David Goulding from the Comparative Medicine Branch and Ms. Lois Wyrick of the Imaging Center at the NIEHS for providing us with photographs and illustrations.

All animal procedures and treatments used in this protocol were in compliance with the NIH/NIEHS animal care guidelines and were approved by the Animal Care and Use Committee (ACUC) at the NIH/NIEHS, Animal Protocol 2010-0004.
1. Preparations
<ol>
	<li>Prepare/purchase recombinant non-propagating lentiviruses carrying your gene of interest. In this study, lentivirus SBI511 expressing copepod green fluorescent protein (copGFP; abbreviated to GFP) from an elongation factor 1a promoter was used...

<ol>
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G., Taylor, L., Sang, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functional+conservation+between+rodents+and+chicken+of+regulatory+sequences+driving+skeletal+muscle+gene+expression+in+transgenic+chickens.">Functional conservation between rodents and chicken of regulatory sequences driving skeletal muscle gene expression in transgenic chickens.</a> BMC Developmental Biology. 10, 26 (2010).</li><li>Zhang, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Production+of+transgenic+pigs+mediated+by+pseudotyped+lentivirus+and+sperm.">Production of transgenic pigs mediated by pseudotyped lentivirus and sperm.</a> PLoS One. 7 (4), e35335 (2012).</li><li>Zhang, Z., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transgenic+quail+production+by+microinjection+of+lentiviral+vector+into+the+early+embryo+blood+vessels.">Transgenic quail production by microinjection of lentiviral vector into the early embryo blood vessels.</a> PLoS One. 7 (12), e50817 (2012).</li><li>Wassarman, P. 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K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Production+of+transgenic+rats+by+lentiviral+transduction+of+male+germ-line+stem+cells.">Production of transgenic rats by lentiviral transduction of male germ-line stem cells.</a> Proceedings of National Academy of Science U S A. 99 (23), 14931-14936 (2002).</li><li>Kanatsu-Shinohara, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Production+of+transgenic+rats+via+lentiviral+transduction+and+xenogeneic+transplantation+of+spermatogonial+stem+cells.">Production of transgenic rats via lentiviral transduction and xenogeneic transplantation of spermatogonial stem cells.</a> Biology of Reproduction. 79 (6), 1121-1128 (2008).</li><li>Dann, C. T., Garbers, D. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Production+of+knockdown+rats+by+lentiviral+transduction+of+embryos+with+short+hairpin+RNA+transgenes.">Production of knockdown rats by lentiviral transduction of embryos with short hairpin RNA transgenes.</a> Methods in Molecular Biology. 450, 193-209 (2008).</li><li>Chandrashekran, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Efficient+generation+of+transgenic+mice+by+lentivirus-mediated+modification+of+spermatozoa.">Efficient generation of transgenic mice by lentivirus-mediated modification of spermatozoa.</a> FASEB Journal. 28 (2), 569-576 (2014).</li><li>Woods, S. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laser-assisted+in+vitro+fertilization+facilitates+fertilization+of+vitrified-warmed+C57BL/6+mouse+oocytes+with+fresh+and+frozen-thawed+spermatozoa,+producing+live+pups.">Laser-assisted in vitro fertilization facilitates fertilization of vitrified-warmed C57BL/6 mouse oocytes with fresh and frozen-thawed spermatozoa, producing live pups.</a> PLoS One. 9 (3), e91892 (2014).</li><li>Tanaka, N., Takeuchi, T., Neri, Q. V., Sills, E. S., Palermo, G. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Laser-assisted+blastocyst+dissection+and+subsequent+cultivation+of+embryonic+stem+cells+in+a+serum/cell+free+culture+system:+applications+and+preliminary+results+in+a+murine+model.">Laser-assisted blastocyst dissection and subsequent cultivation of embryonic stem cells in a serum/cell free culture system: applications and preliminary results in a murine model.</a> Journal of Translational Medicine. 4, 20 (2006).</li><li>Martin, N. P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=En+masse+lentiviral+gene+delivery+to+mouse+fertilized+eggs+via+laser+perforation+of+zona+pellucida.">En masse lentiviral gene delivery to mouse fertilized eggs via laser perforation of zona pellucida.</a> Transgenic Research. 27 (1), 39-49 (2018).</li><li>Lawitts, J. A., Biggers, J. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Culture+of+preimplantation+embryos.">Culture of preimplantation embryos.</a> Methods in Enzymology. 225, 153-164 (1993).</li><li>Stein, P., Schindler, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mouse+oocyte+microinjection,+maturation+and+ploidy+assessment.">Mouse oocyte microinjection, maturation and ploidy assessment.</a> Journal of Visualized Experiments. (53), (2011).</li><li>Nagy, A., Gertsenstein, M., Vintersten, K., Behringer, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Caesarean+section+and+fostering.">Caesarean section and fostering.</a> CSH Protocols. 2006 (2), (2006).</li><li>Chum, P. Y., Haimes, J. D., Andre, C. P., Kuusisto, P. K., Kelley, M. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genotyping+of+plant+and+animal+samples+without+prior+DNA+purification.">Genotyping of plant and animal samples without prior DNA purification.</a> Journal of Visualized Experiments. (67), (2012).</li><li>Bin Ali, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Improved+pregnancy+and+birth+rates+with+routine+application+of+nonsurgical+embryo+transfer.">Improved pregnancy and birth rates with routine application of nonsurgical embryo transfer.</a> Transgenic Research. 23 (4), 691-695 (2014).</li><li>Liu, K. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Integrase-deficient+lentivirus:+opportunities+and+challenges+for+human+gene+therapy.">Integrase-deficient lentivirus: opportunities and challenges for human gene therapy.</a> Current Gene Therapy. 14 (5), 352-364 (2014).</li><li>Sauvain, M. O., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genotypic+features+of+lentivirus+transgenic+mice.">Genotypic features of lentivirus transgenic mice.</a> Journal of Virology. 82 (14), 7111-7119 (2008).</li></ol>

The ability of the lentiviruses to integrate into their host genome makes them an ideal vector for stable gene delivery. Lentiviral vectors can carry up to 8.5 kilobase pair (kbp) of genetic material that can accommodate cell-specific or inducible promoters, selection markers, or fluorescent moieties. Incorporated genomic material can replicate as part of their host genome and be regulated to express or deactivate at desired time points. These vectors allow for spatiotemporal control over gene expression at various stage...

This method provides detailed instructions for permeabilizing the zona pellucida of mouse fertilized eggs to make embryonic cells accessible for gene delivery by lentiviruses. Lentiviruses are designed by nature for efficient gene delivery to mammalian cells. They infect dividing and non-dividing cells and integrate the lentiviral genome into their host chromosomes1. The range of lentiviral host cells is readily expanded by pseudotyping the recombinant lentivirus with the vesicular stomatitis virus glycoprotein (VSV-G), due to the broad tropism of the VSV-G protein2. Following transduction, lentiviral genes are stably integrated and expressed as part of their host chromosomes creating an ideal tool for generating transgenic animals. If delivered to early stage embryonic cells, the lentiviral genome is replicated and expressed in the entire organism. Lentiviral transduction has led to the production of mice, rat, chicken, quail and pig3,4,5,6,7 among other species of transgenics. The typical method of lentiviral gene delivery, however, requires skilled technicians and specialized equipment to overcome the zona pellucida barrier that encapsulates the early stage embryos. The overall goal of this method is to describe how to permeabilize the zona using a laser to facilitate lentiviral gene delivery.
Mammalian eggs are surrounded by the zona pellucida which hardens following fertilization to protect the fertilized eggs against polyspermy and to limit environmental interactions8,9. The zona forms a barrier that keeps lentiviruses away from the embryonic cells until the embryos are hatched as a blastocyst. Cultured mouse fertilized eggs hatch after 4 days and must be implanted into pseudopregnant mice prior to hatching for normal development into pups. Therefore, for transduction, lentiviruses are microinjected before hatching from the zona into the perivitelline cavity, the space between the zona and the embryonic cells.
The zona pellucida is often removed for in vitro fertilization of human eggs to increase the fertilization rate10. However, chemical removal of mouse zona pellucida adversely affects mouse embryo development and is harmful to embryonic cells11,12. Other methods for gene delivery to mouse fertilized eggs overcome the zona pellucida barrier by direct microinjection of DNA into the cell nucleus13. Pronuclear microinjection is an efficient means of delivering genes to embryos. However, since each embryo is held in place individually for microinjection, the practice can be laborious and time consuming for a novice user.
Other methods such as electroporation and photoporation are useful for transient and short-term gene delivery to mouse fertilized eggs14,15,16. These methods are extensively used for delivering CRISPR-Cas9 components and recombinases. However, electroporation and photoporation delivery of genes cannot be used efficiently to create transgenics. Spermatozoa that are collected from punctured mouse epididymis can also be transduced by lentiviruses and used for in vitro fertilization to produce transgenic animals17,18,19,20.
In this protocol, the lentiviral gene delivery to mouse embryos is facilitated by permeabilizing the zona using a laser. The XYClone laser was developed as an aid for in vitro fertilization21 and cultivation of embryonic stem cells22. It is a small apparatus that is simple to setup and easy to use. Once installed on a microscope, it occupies the space of an objective lens and the accompanying software allows for aiming the laser while looking through the microscope eyepieces (see Protocol: section 3). Once the zona is perforated by the XYClone laser, lentiviruses can be introduced into the culture media for gene delivery23. Multiple lentiviruses could be used to simultaneously deliver several genes for chromosomal incorporation.
This protocol will describe how to isolate and culture mouse fertilized eggs, illustrates the use of laser for perforation of the zona pellucida, and demonstrates the transduction of mouse embryonic cells by lentiviruses.

<table>
	<tbody>
		<tr>
			<td>CD510B-1 plasmid</td>
			<td>System Biosciences</td>
			<td>CD510B-1</td>
			<td>used to package the lentivirus expressing EF1a-copGFP</td>
		</tr>
		<tr>
			<td>Dimethylpolysiloxane</td>
			<td>Sigma</td>
			<td>DMPS5X</td>
			<td>culturing embryos</td>
		</tr>
		<tr>
			<td>hyaluronidase</td>
			<td>Sigma</td>
			<td>H3506</td>
			<td>used to remove cumulus cells</td>
		</tr>
		<tr>
			<td>XYClone Laser</td>
			<td>Hamilton Thorne Biosciences</td>
			<td></td>
			<td>perforating mouse fertilized eggs</td>
		</tr>
		<tr>
			<td>Non-Surgical Embryo Transfer (NSET) Device</td>
			<td>ParaTechs</td>
			<td>60010</td>
			<td>NSET of embryos</td>
		</tr>
		<tr>
			<td>KSOM medium</td>
			<td>Millipore</td>
			<td>MR-020P-5F</td>
			<td>culturing embryos</td>
		</tr>
		<tr>
			<td>Composition of KSOM:</td>
			<td></td>
			<td></td>
			<td>mg/100mL</td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td></td>
			<td></td>
			<td>555</td>
		</tr>
		<tr>
			<td>KCl</td>
			<td></td>
			<td></td>
			<td>18.5</td>
		</tr>
		<tr>
			<td>KH2PO4</td>
			<td></td>
			<td></td>
			<td>4.75</td>
		</tr>
		<tr>
			<td>MgSO4 7H2O</td>
			<td></td>
			<td></td>
			<td>4.95</td>
		</tr>
		<tr>
			<td>CaCl2 2H2O</td>
			<td></td>
			<td></td>
			<td>25</td>
		</tr>
		<tr>
			<td>NaHCO3</td>
			<td></td>
			<td></td>
			<td>210</td>
		</tr>
		<tr>
			<td>Glucose</td>
			<td></td>
			<td></td>
			<td>3.6</td>
		</tr>
		<tr>
			<td>Na-Pyruvate</td>
			<td></td>
			<td></td>
			<td>2.2</td>
		</tr>
		<tr>
			<td>DL-Lactic Acid, sodium salt</td>
			<td></td>
			<td></td>
			<td>0.174mL</td>
		</tr>
		<tr>
			<td>10mM EDTA</td>
			<td></td>
			<td></td>
			<td>100&#181;L</td>
		</tr>
		<tr>
			<td>Streptomycin</td>
			<td></td>
			<td></td>
			<td>5</td>
		</tr>
		<tr>
			<td>Penicillin</td>
			<td></td>
			<td></td>
			<td>6.3</td>
		</tr>
		<tr>
			<td>0.5% phenol red</td>
			<td></td>
			<td></td>
			<td>0.1mL</td>
		</tr>
		<tr>
			<td>L-Glutamine</td>
			<td></td>
			<td></td>
			<td>14.6</td>
		</tr>
		<tr>
			<td>MEM Essential Amino Acids</td>
			<td></td>
			<td></td>
			<td>1mL</td>
		</tr>
		<tr>
			<td>MEM Non-essential AA</td>
			<td></td>
			<td></td>
			<td>0.5mL</td>
		</tr>
		<tr>
			<td>BSA</td>
			<td></td>
			<td></td>
			<td>100</td>
		</tr>
		<tr>
			<td>M2 medium</td>
			<td>Millipore</td>
			<td>MR-015-D</td>
			<td>culturing embryos</td>
		</tr>
		<tr>
			<td>Composition of M2:</td>
			<td></td>
			<td></td>
			<td>mg/100mL</td>
		</tr>
		<tr>
			<td>Calcium Chloride</td>
			<td></td>
			<td></td>
			<td>25.1</td>
		</tr>
		<tr>
			<td>Magnesium Sulfate (anhydrous)</td>
			<td></td>
			<td></td>
			<td>16.5</td>
		</tr>
		<tr>
			<td>Potassium Chloride</td>
			<td></td>
			<td></td>
			<td>35.6</td>
		</tr>
		<tr>
			<td>Potassium Phosphate, Monobasic</td>
			<td></td>
			<td></td>
			<td>16.2</td>
		</tr>
		<tr>
			<td>Sodium Bicarbonate</td>
			<td></td>
			<td></td>
			<td>35</td>
		</tr>
		<tr>
			<td>Sodium Chloride</td>
			<td></td>
			<td></td>
			<td>553.2</td>
		</tr>
		<tr>
			<td>Albumin, Bovine Fraction</td>
			<td></td>
			<td></td>
			<td>400</td>
		</tr>
		<tr>
			<td>D-Glucose</td>
			<td></td>
			<td></td>
			<td>100</td>
		</tr>
		<tr>
			<td>Na-HEPES</td>
			<td></td>
			<td></td>
			<td>54.3</td>
		</tr>
		<tr>
			<td>Phenol Red</td>
			<td></td>
			<td></td>
			<td>1.1</td>
		</tr>
		<tr>
			<td>Pyruvic Acid</td>
			<td></td>
			<td></td>
			<td>3.6</td>
		</tr>
		<tr>
			<td>DL-Lactic Acid</td>
			<td></td>
			<td></td>
			<td>295</td>
		</tr>
	</tbody>
</table>

laser-assisted lentiviral gene delivery to mouse fertilized eggs

Lentiviruses are efficient vectors for gene delivery to mammalian cells. Following transduction, the lentiviral genome is stably incorporated into the host chromosome and is passed on to progeny. Thus, they are ideal vectors for creation of stable cell lines, in vivo delivery of indicators, and transduction of single cell fertilized eggs to create transgenic animals. However, mouse fertilized eggs and early stage embryos are protected by the zona pellucida, a glycoprotein matrix that forms a barrier against lentiviral gene delivery. Lentiviruses are too large to penetrate the zona and are typically delivered by microinjection of viral particles into the perivitelline cavity, the space between the zona and the embryonic cells. The requirement for highly skilled technologists and specialized equipment has minimized the use of lentiviruses for gene delivery to mouse embryos. This article describes a protocol for permeabilizing the mouse fertilized eggs by perforating the zona with a laser. Laser-perforation does not result in any damage to embryos and allows lentiviruses to gain access to embryonic cells for gene delivery. Transduced embryos can develop into blastocyst in vitro, and if implanted in pseudopregnant mice, develop into transgenic pups. The laser used in this protocol is effective and easy to use. Genes delivered by lentiviruses stably incorporate into mouse embryonic cells and are germline transmittable. This is an alternative method for creation of transgenic mice that requires no micromanipulation and microinjection of fertilized eggs.

Development of isolated/transduced mouse fertilized eggs can be checked under the microscope daily (Figure 1). Healthy embryos develop into blastocyst within 3&#8211;4 days. In this protocol, 60&#8211;70% of untreated embryos develop into blastocyst23. Out of 114 laser-perforated transduced embryos, 54 developed into blastocyst (rate of 47%) and 46 blastocysts expressed GFP (46/54=85%)23.
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Laser-assisted Lentiviral Gene Delivery to Mouse Fertilized Eggs

Mouse fertilized eggs and early stage embryos are protected by the zona pellucida, a glycoprotein matrix that forms a barrier against gene delivery. This article describes a protocol for perforating the zona with a laser to transduce embryonic cells with lentiviral vectors and to create transgenic mice.

Lentiviruses are efficient vectors for gene delivery to mammalian cells. Following transduction, the lentiviral genome is stably incorporated into the ...

This is an alternate and easy to use method for delivering genes of interest to fertilized mouse eggs via laser perforation of the zona pellucida and lentiviral gene delivery. Laser-assisted perforation of the mouse donor procedure may also be applicable to the fertilized eggs of other species for facilitating the entry of other types of viruses or transfection reagents. The main advantage of this technique is that it requires no specialized skills for the micromanipulation and micro injection of the fertilized mouse eggs.Demonstrating fertilized mouse egg isolation procedure will be Page Myers, a research scientist from the Comparative Medicine branch at the NIEHS. 16 to 24 hours post mating, isolate the ovaries and ovaducts from female mice with vaginal plugs, according to standard protocols. When all of the tissues have been collected, tear the ampulla of each ovary apart, and release the fertilized eggs, surrounded by cumulous cells, and transfer the eggs in cumulous cells to a 35 millimeter dish containing one x hyaluronidase in fresh M2 medium, for a three to five minute incubation at room temperature.Pipette the eggs a few times to release the cumulous cells, and transfer the eggs to a new 35 millimeter dish containing M2 medium, with pipetting to wash off the enzyme. Next, transfer the washed eggs into a 35 millimeter dish containing potassium simplex optimized medium, or KSOM, and pipette to wash off the remaining M2 medium and hyaluronidase. Then, transfer the eggs to 35 millimeter tissue-culture treated plates seeded with 50 microliters of KSOM and two milliliters of dimethylpolysiloxane for a two hour equilibration at 37 degrees Celsius, 5%carbon dioxide and oxygen, and 90%nitrogen.While the eggs are in the incubator, set up and calibrate the XYClone laser, according to the manufacturer's recommendations. When the eggs are ready, place the first drop plate onto the laser microscope stage, and manually focus the zona pellucida. After confirming that the laser LED light is visible through the objective, move the microscope stage to target the zona with the LED laser, and use the computer software to set the XYClone laser to 250 microseconds.Adjust the LED light size to the appropriate dimensions, and perforate the zona pellucida of each egg three times with the laser to produce three 10-micrometer holes. It is critical to perform the perforation quickly, but carefully, as the fertilized eggs can not keep outside of the incubator for longer than 15 minutes. Then, return the perforated eggs to the incubator for another two hours.At the end of the second incubation, treat the 50 microliter KSOM drop with two microliters of concentrated lentivirus without mixing. And return the eggs to the incubator for four days. When the eggs have developed into blastocysts, use a non-surgical embryo transfer device, to deposit approximately 10-15 embryos in an about two microliters of KSOM.17 days after the embryo transfer, allow the pregnant mouse to give birth naturally or collect the neonates by cesarean section as necessary. Then, collect tissue from the pups for genotyping, to determine the rate of transgenesis. Isolated and transduced mouse-fertilized egg development can be checked under the microscope daily.60 to 70%of healthy, untreated embryos develop into blastocysts within three to four days. While about 47%of laser-perforated, transduced embryos develop into blastocysts, 85%of which express the tranduced gene of interest. Aiming the laser to thin the zona, instead of creating a hole, allows the developing embryos to benefit from an intact, encapsulating zona pellucida while remaining permissive to lentiviral transduction.Transduction with a recombinant lentivirus, expressing copepod GFP from an elongation factor 1A promoter induces multiple lentiviral integrations, and a high expression of GFP under a blue LED lamp. While attempting this procedure, it is important to remember that, while the ability of lentiviruses to integrate into the host genome makes them a powerful tool for stable gene delivery, but random integration may also introduce insertional mutations. This technique could enable researchers in the field of genetics to rapidly develop transgenic animal models for the study of disease for in vivo protein production, or for functional gene studies.Following this procedure, other methods like immunohistochemistry can be performed on isolated tissue samples from transduced pups to answer additional questions about the location and the extent of gene expression in various tissues of interest. Don't forget that working with lentiviruses can be extremely hazardous. Therefore please follow your institutional guidelines for working with lentiviruses.Wear personal protective clothes and decontaminate all waste prior to disposal.

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Windowing Chicken Eggs for Developmental Studies

The study of development has been greatly aided by the use of the chick embryo as an experimental model.  The ease of accessibility of the embryo has allowed for experiments to map cell fates using several approaches, including chick quail chimeras and focal dye labeling.  In addition, it allows for molecular perturbations of several types, including placement of protein-coated beads and introduction of plasmid DNA using in ovo electroporation.  These experiments have yielded important data on the development of the central and peripheral nervous systems.  For many of these studies, it is necessary to open the eggshell and reclose it without perturbing the embryo's growth.  The embryo can be examined at successive developmental stages by re-opening the eggshell.  While there are several excellent methods for opening chicken eggs, in this article we demonstrate one method that has been optimized for long survival times.  In this method, the egg rests on its side and a small window is cut in the shell.  After the experimental procedure, the shell is used to cover the egg for the duration of its development.  Clear plastic tape overlying the eggshell protects the embryo and helps retain hydration during the remainder of the incubation period.  This method has been used beginning at two days of incubation and has allowed survival through mature embryonic ages.

The ease of accessibility of the embryo has allowed for experiments to map cell fates using several approaches, including chick quail chimeras and focal dye labeling. In this article we demonstrate one egg preparation method that has been optimized for long survival times.

The study of development has been greatly aided by the use of the chick embryo as an experimental model.  The ease of accessibility of the embryo has ...

Obtaining Eggs from Xenopus laevis Females

The eggs of Xenopus laevis intact, lysed, and/or fractionated are useful for a wide variety of experiments. This protocol shows how to induce egg laying, collect and dejelly the eggs, and sort the eggs to remove any damaged eggs.

The eggs of Xenopus laevis intact, lysed, and/or fractionated are useful for a wide variety of experiments. This protocol shows how to induce egg laying, collect and dejelly the eggs, and sort the eggs to remove any damaged eggs.

The eggs of Xenopus laevis intact, lysed, and/or fractionated are useful for a wide variety of experiments. This protocol shows how to induce egg laying, ...

Using the Gene Pulser MXcell Electroporation System to Transfect Primary Cells with High Efficiency

It is becoming increasingly apparent that electroporation is the most effective way to introduce plasmid DNA or siRNA into primary cells. The Gene Pulser MXcell electroporation system and Gene Pulser electroporation buffer (Bio-Rad) were specifically developed to easily transfect nucleic acids into mammalian cells and difficult-to-transfect cells, such as primary and stem cells. We will demonstrate how to perform a simple experiment to quickly identify the best electroporation conditions. We will demonstrate how to run several samples through a range of electroporation conditions so that an experiment can be conducted at the same time as optimization is performed. We will also show how optimal conditions identified using 96-well electroporation plates can be used with standard electroporation cuvettes, facilitating the switch from electroporation plates to electroporation cuvettes while maintaining the same electroporation efficiency. In the video, we will also discuss some of the key factors that can lead to the success or failure of electroporation experiments.

This procedure shows how to use the Gene Pulser MXcell electroporation system to rapidly and easily identify the best electroporation conditions for mouse embryonic fibroblasts (MEFs) or other primary cells. Considerations for troubleshooting are also discussed in the associated video.

It is becoming increasingly apparent that electroporation is the most effective way to introduce plasmid DNA or siRNA into primary cells. The Gene Pulser ...

Using an Automated Cell Counter to Simplify Gene Expression Studies: siRNA Knockdown of IL-4 Dependent Gene Expression in Namalwa Cells

The use of siRNA mediated gene knockdown is continuing to be an important tool in studies of gene expression.  siRNA studies are being conducted not only to study the effects of downregulating single genes, but also to interrogate signaling pathways and other complex interaction networks.  These pathway analyses require both the use of relevant cellular models and methods that cause less perturbation to the cellular physiology.  Electroporation is increasingly being used as an effective way to introduce siRNA and other nucleic acids into difficult to transfect cell lines and primary cells without altering the signaling pathway under investigation. There are multiple critical steps to a successful siRNA experiment, and there are ways to simplify the work while improving the data quality at several experimental stages.  To help you get started with your siRNA mediated gene knockdown project, we will demonstrate how to perform a pathway study complete from collecting and counting the cells prior to electroporation through post transfection real-time PCR gene expression analysis.  The following study investigates the role of the transcriptional activator STAT6 in IL-4 dependent gene expression of CCL17 in a Burkitt lymphoma cell line (Namalwa).  The techniques demonstrated are useful for a wide range of siRNA-based experiments on both adherent and suspension cells.  We will also show how to streamline cell counting with the TC10 automated cell counter, how to electroporate multiple samples simultaneously using the MXcell electroporation system, and how to simultaneously assess RNA quality and quantity with the Experion automated electrophoresis system.

This procedure describes a quick and easy workflow to introduce siRNA into difficult to transfect cell lines and follow gene expression by real-time PCR. Use of an automated cell counter, multi-well electroporation plate, and automated electrophoresis station provide quick and reliable results without the need for expensive robotic handling.

The use of siRNA mediated gene knockdown is continuing to be an important tool in studies of gene expression.  siRNA studies are being conducted not only ...

In vivo Imaging and Therapeutic Treatments in an Orthotopic Mouse Model of Ovarian Cancer

Human cancer and response to therapy is better represented in orthotopic animal models. This paper describes the development of an orthotopic mouse model of ovarian cancer, treatment of cancer via oral delivery of drugs, and monitoring of tumor cell behavior in response to drug treatment in real time using in vivo imaging system. In this orthotopic model, ovarian tumor cells expressing luciferase are applied topically by injecting them directly into the mouse bursa where each ovary is enclosed. Upon injection of D-luciferin, a substrate of firefly luciferase, luciferase-expressing cells generate bioluminescence signals. This signal is detected by the in vivo imaging system and allows for a non-invasive means of monitoring tumor growth, distribution, and regression in individual animals. Drug administration via oral gavage allows for a maximum dosing volume of 10 mL/kg body weight to be delivered directly to the stomach and closely resembles delivery of drugs in clinical treatments. Therefore, techniques described here, development of an orthotopic mouse model of ovarian cancer, oral delivery of drugs, and in vivo imaging, are useful for better understanding of human ovarian cancer and treatment and will improve targeting this disease.

In vivo Imaging and Therapeutic Treatments in an Orthotopic Mouse Model of Ovarian Cancer

Orthotopic animal models of ovarian cancer replicate better human disease and therefore enhance our understanding of cancer progression and tumor response to therapy. A mouse model receives an intrabursal injection of luciferase-expressing ovarian tumor cells. Treatment is administered via oral gavage. Tumor growth is monitored by in vivo imaging system.

Human cancer and response to therapy is better represented in orthotopic animal models.  This paper describes the development of an orthotopic mouse model ...

Isolation and Culture of Cells from the Nephrogenic Zone of the Embryonic Mouse Kidney

Embryonic development of the kidney has been extensively studied both as a model for epithelial-mesenchymal interaction in organogenesis and to gain understanding of the origins of congenital kidney disease. More recently, the possibility of steering na&iuml;ve embryonic stem cells toward nephrogenic fates has been explored in the emerging field of regenerative medicine. Genetic studies in the mouse have identified several pathways required for kidney development, and a global catalog of gene transcription in the organ has recently been generated <a href="http://www.gudmap.org/">http://www.gudmap.org/</a>, providing numerous candidate regulators of essential developmental functions. Organogenesis of the rodent kidney can be studied in organ culture, and many reports have used this approach to analyze outcomes of either applying candidate proteins or knocking down the expression of candidate genes using siRNA or morpholinos. However, the applicability of organ culture to the study of signaling that regulates stem/progenitor cell differentiation versus renewal in the developing kidney is limited as cultured organs contain a compact extracellular matrix limiting diffusion of macromolecules and virus particles. To study the cell signaling events that influence the stem/progenitor cell niche in the kidney we have developed a primary cell system that establishes the nephrogenic zone or progenitor cell niche of the developing kidney ex vivo in isolation from the epithelial inducer of differentiation. Using limited enzymatic digestion, nephrogenic zone cells can be selectively liberated from developing kidneys at E17.5. Following filtration, these cells can be cultured as an irregular monolayer using optimized conditions. Marker gene analysis demonstrates that these cultures contain a distribution of cell types characteristic of the nephrogenic zone in vivo, and that they maintain appropriate marker gene expression during the culture period. These cells are highly accessible to small molecule and recombinant protein treatment, and importantly also to viral transduction, which greatly facilitates the study of candidate stem/progenitor cell regulator effects. Basic cell biological parameters such as proliferation and cell death as well as changes in expression of molecular markers characteristic of nephron stem/progenitor cells in vivo can be successfully used as experimental outcomes. Ongoing work in our laboratory using this novel primary cell technique aims to uncover basic mechanisms governing the regulation of self-renewal versus differentiation in nephron stem/progenitor cells.

In this report we describe a method for the isolation and culture of the progenitor cell niche from the embryonic mouse kidney that can be used to study signaling pathways regulating stem/progenitor cells of the developing kidney. These cultured cells are highly accessible to small molecule and recombinant protein treatment, and importantly also to viral transduction, which allows efficient manipulation of candidate pathways.

Embryonic development of the kidney has been extensively studied both as a model for epithelial-mesenchymal interaction in organogenesis and  to gain ...

Using SecM Arrest Sequence as a Tool to Isolate Ribosome Bound Polypeptides

Extensive research has provided ample evidences suggesting that protein folding in the cell is a co-translational process1-5. However, the exact pathway that polypeptide chain follows during co-translational folding to achieve its functional form is still an enigma. In order to understand this process and to determine the exact conformation of the co-translational folding intermediates, it is essential to develop techniques that allow the isolation of RNCs carrying nascent chains of predetermined sizes to allow their further structural analysis.
SecM (secretion monitor) is a 170 amino acid E. coli protein that regulates expression of the downstream SecA (secretion driving) ATPase in the secM-secA operon6. Nakatogawa and Ito originally found that a 17 amino acid long sequence (150-FSTPVWISQAQGIRAGP-166) in the C-terminal region of the SecM protein is sufficient and necessary to cause stalling of SecM elongation at Gly165, thereby producing peptidyl-glycyl-tRNA stably bound to the ribosomal P-site7-9. More importantly, it was found that this 17 amino acid long sequence can be fused to the C-terminus of virtually any full-length and/or truncated protein thus allowing the production of RNCs carrying nascent chains of predetermined sizes7. Thus, when fused or inserted into the target protein, SecM stalling sequence produces arrest of the polypeptide chain elongation and generates stable RNCs both in vivo in E. coli cells and in vitro in a cell-free system. Sucrose gradient centrifugation is further utilized to isolate RNCs.
The isolated RNCs can be used to analyze structural and functional features of the co-translational folding intermediates. Recently, this technique has been successfully used to gain insights into the structure of several ribosome bound nascent chains10,11. Here we describe the isolation of bovine Gamma-B Crystallin RNCs fused to SecM and generated in an in vitro translation system.

We describe here a technique that is now routinely used to isolate stably bound ribosome nascent chain complexes (RNCs). This technique takes advantage of the discovery that a 17 amino acid long SecM "arrest sequence" can halt translation elongation in a prokaryotic (E. coli) system, when inserted into (or fused to the C-terminus) of virtually any protein.

Extensive research has provided ample evidences suggesting that protein folding in the cell is a co-translational process1-5. However, the exact pathway ...

Intraductal Injection for Localized Drug Delivery to the Mouse Mammary Gland

Herein we describe a protocol to deliver various reagents to the mouse mammary gland via intraductal injections. Localized drug delivery and knock-down of genes within the mammary epithelium has been difficult to achieve due to the lack of appropriate targeting molecules that are independent of developmental stages such as pregnancy and lactation. Herein, we describe a technique for localized delivery of reagents to the mammary gland at any stage in adulthood via intraductal injection into the nipples of mice. The injections can be performed on live mice, under anesthesia, and allow for a non-invasive and localized drug delivery to the mammary gland. Furthermore, the injections can be repeated over several months without damaging the nipple. Vital dyes such as Evans Blue are very helpful to learn the technique. Upon intraductal injection of the blue dye, the entire ductal tree becomes visible to the eye. Furthermore, fluorescently labeled reagents also allow for visualization and distribution within the mammary gland. This technique is adaptable for a variety of compounds including siRNA, chemotherapeutic agents, and small molecules.

A protocol for the non-invasive intraductal delivery of aqueous reagents to the mouse mammary gland is described. The method takes advantage of localized injection into the nipples of mammary glands targeting mammary ducts specifically. This technique is adaptable for a variety of compounds including siRNA, chemotherapeutic agents and small molecules.

Herein we describe a protocol to deliver various reagents to the mouse mammary gland via intraductal injections. Localized drug delivery and knock-down of ...

Transient Expression of Proteins by Hydrodynamic Gene Delivery in Mice

Efficient expression of transgenes in vivo is of critical importance in studying gene function and developing treatments for diseases. Over the past years, hydrodynamic gene delivery (HGD) has emerged as a simple, fast, safe and effective method for delivering transgenes into rodents. This technique relies on the force generated by the rapid injection of a large volume of physiological solution to increase the permeability of cell membranes of perfused organs and thus deliver DNA into cells. One of the main advantages of HGD is the ability to introduce transgenes into mammalian cells using naked plasmid DNA (pDNA). Introducing an exogenous gene using a plasmid is minimally laborious, highly efficient and, contrary to viral carriers, remarkably safe. HGD was initially used to deliver genes into mice, it is now used to deliver a wide range of substances, including oligonucleotides, artificial chromosomes, RNA, proteins and small molecules into mice, rats and, to a limited degree, other animals. This protocol describes HGD in mice and focuses on three key aspects of the method that are critical to performing the procedure successfully: correct insertion of the needle into the vein, the volume of injection and the speed of delivery. Examples are given to show the application of this method to the transient expression of two genes that encode secreted, primate-specific proteins, apolipoprotein L-I (APOL-I) and haptoglobin-related protein (HPR).

In vivo transfection of naked DNA by hydrodynamic gene delivery introduces genes into the tissue of an animal with minimal inflammatory response. Sufficient amounts of gene product are generated such that gene function and regulation as well as protein structure and function can be analyzed.

Efficient expression of transgenes in vivo is of critical importance in studying gene function and developing treatments for diseases. Over the past ...

Phage-mediated Delivery of Targeted sRNA Constructs to Knock Down Gene Expression in E. coli

RNA-mediated knockdowns are widely used to control gene expression. This versatile family of techniques makes use of short RNA (sRNA) that can be synthesized with any sequence and designed to complement any gene targeted for silencing. Because sRNA constructs can be introduced to many cell types directly or using a variety of vectors, gene expression can be repressed in living cells without laborious genetic modification. The most common RNA knockdown technology, RNA interference (RNAi), makes use of the endogenous RNA-induced silencing complex (RISC) to mediate sequence recognition and cleavage of the target mRNA. Applications of this technique are therefore limited to RISC-expressing organisms, primarily eukaryotes. Recently, a new generation of RNA biotechnologists have developed alternative mechanisms for controlling gene expression through RNA, and so made possible RNA-mediated gene knockdowns in bacteria. Here we describe a method for silencing gene expression in E. coli that functionally resembles RNAi. In this system a synthetic phagemid is designed to express sRNA, which may designed to target any sequence. The expression construct is delivered to a population of E. coli cells with non-lytic M13 phage, after which it is able to stably replicate as a plasmid. Antisense recognition and silencing of the target mRNA is mediated by the Hfq protein, endogenous to E. coli. This protocol includes methods for designing the antisense sRNA, constructing the phagemid vector, packaging the phagemid into M13 bacteriophage, preparing a live cell population for infection, and performing the infection itself. The fluorescent protein mKate2 and the antibiotic resistance gene chloramphenicol acetyltransferase (CAT) are targeted to generate representative data and to quantify knockdown effectiveness.

Phage-mediated Delivery of Targeted sRNA Constructs to Knock Down Gene Expression in E. coli

We describe a method to knock down gene expression in a growing population of E. coli cells using sequence-targeted sRNA expression cassettes delivered by an M13 phagemid vector.